In English | ISSUE 4/2024
Physical modelling of pipecooled massive concrete.
High temperatures due to heat of hydration are a common phenomenon in early-age massive concrete structures. As too high maximum temperatures and temperature differences may cause strength and durability problems in concrete, the temperature of concrete during hardening must be limited according to by78 and other instructions. One method to control the temperature of early-age concrete is pipe-cooling which Henri Tähkänen from Aalto University considered in his master’s thesis called Physical modelling of pipe-cooled massive concrete.
The purpose of the thesis was to simulate the temperature distribution, thermal stresses, and cracking of early-age massive concrete with waterpipe cooling system to make sure that the maximum temperatures and temperature differences stay between the limit values and that concrete does not crack excessively. The modelling was performed using two- and three-dimensional calculation models based on finite element method. The aim of the modelling was to evaluate the effects of different pipecooling parameters and concrete geometry on the temperature distribution, thermal stresses and cracking of concrete.
Results concluded that pipe-cooling can effectively control the maximum temperature and temperature differences of early-age concrete. It also reduces thermal stresses at the outer surface of concrete structure which improves the durability of concrete. The distance between cooling pipes, concrete initial temperature and the flow rate of cooling water were found to be the most effective parameters controlling the temperature of pipe-cooled concrete. The effects of geometry on the temperature distribution of concrete are mostly Limited to areas which join cooled and non-cooled concrete. The required distance between cooling pipes and the effects of different cooling parameters on the maximum temperature of concrete can be evaluated utilizing simple tables or calculation models presented in the thesis.
